OF LIFE IN GENERAL. 331 



is generally regarded as one of the specific characters 

 of the rabbit. Finally, two male Porto Santo rabbits, 

 when kept in captivity, never lost their extreme wild- 

 ness, and would never associate or breed with the 

 females of various breeds placed with them. 



To what extent these remarkable changes were the 

 direct result of a changed environment, it is, of course, 

 impossible to say; but it was proved that at least the 

 colouring was a direct effect. Thus one of the feral 

 rabbits, after being kept for four years in captivity, 

 was found by Darwin to have acquired a blackish gray 

 fur on the upper surface of the tail and the edges of 

 the ears, whilst the whole body was much less red; i. e., 

 it had recovered the proper colour of its fur after four 

 years of English climate. 



The influence of domestication combined with arti- 

 ficial selection is well known to everyone, but what 

 shares of the changes produced are to be assigned to 

 each of these agencies is, as a rule, quite indeterminable. 

 However, one may with some reservation ascribe to 

 domestication changes effected in characters which 

 have never been the subject of selection. For instance, 

 the weight of the rabbit was found by Darwin to in- 

 crease on domestication, the result, probably, both of 

 more ample feeding and of artificial selection. The 

 skull capacity, on the other hand, by no means propor- 

 tionately increased in size, and as this is scarcely a 

 character on which selection would be practised, we 

 may consider the relative diminution as probably due 

 to the direct influence of domestication. The reason 

 why we cannot say with absolute certainty that it is a 

 direct effect, lies in the fact that the character of 



